<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../vue.js"></script>
</head>

<body>
    <div id="app">
        <button @click = "isHot = !isHot">点击切换天气</button><br/>
        <p>今天天气真{{isHot ? "热" : "冷"}}啊</p>

        <img :src="src" alt="">

    </div>
    <script>
        Vue.config.productionTip = false;
        
        const vm = new Vue({
            el: "#app",
            data() {
                return {
                    isHot: true,
                    src: ""
                }
            },
            watch:{
                isHot:{
                    immediate: true,
                    handler(newIsHot){
                        newIsHot ? this.src = "./png-0015.png" : this.src = "./png-0018.png"
                    }
                }
            }
        })
    </script>
</body>

</html>